Ulster are hopeful that hooker Rob Herring will be fit for the trip to Leinster on New Year's Day after he was ruled out of Friday's game against Connacht at Kingspan Stadium.

Ulster defence coach Jonny Bell said the injury "wasn't too serious".

"It gives him a chance of being back for Leinster but we'll have to wait and see," said Bell.

Fly-half Billy Burns is a fitness doubt for Friday's United Rugby Championship fixture with a bicep injury after he sustained in the European Pool 2 victory over Racing.

"Uncertain at the minute, we'll find out tomorrow (Wednesday)," Bell said of Burns' availability for the visit of Connacht to Belfast.

"We'll see how he trains or if he trains tomorrow. He'd had a bicep issue which altering the function in his arm and as a 10 he needs to be able to pass the ball, so we'll wait and see on that."

Luke Marshall, who injured his ankle in training last week, is unavailable for selection for the pre-Christmas match.

On a more positive note, flanker and long-term absentee Sean Reffell has resumed full training and is now available for selection following the ankle injury he sustained last January.

A squad update, issued by Ulster prior to Bell's news conference, also revealed that wing Ethan McIlroy has returned to team training this week.

McIlroy sustained a facial fracture and concussion during the home URC win over Munster.

The update confirmed that Burns' availability for Ulster's second meeting of the season with Connacht "will be assessed during the week".

The westerners ran out 22-20 winners over Dan McFarland's side at the Sportsground in Galway in early November.

That win took Peter Wilkins' side top of the URC table, but they have now lost five of their last six outings in all competitions, including three reverses in league action.

Ulster lost their last two URC matches against Glasgow and Edinburgh but should take confidence from their success over the Top 14 leaders on Saturday.

Connacht are expected to welcome back Mack Hansen for Friday's match after the Ireland wing sat out his side's defeat by Saracens at the weekend with a foot problem.

Ulster sit seventh in the standings after seven rounds of fixtures, with their opponents on Friday one point worse off in eighth.